Mechanical aircraft navigation computer

ABSTRACT

A relatively small, box-like housing contains a pair of spaced parallel shafts journalled in bearings at the opposite ends of the box. A plurality of endless belts are threaded over pulleys or drums mounted on the shafts. Scales of any suitable data or indicia are printed on the belts and displayed through corresponding windows in the cover of the box. Each shaft has one or more clutches interposed between the drums supporting the belts so that, when disengaged, the position of each belt may be changed relative to the positions of the other belts. When any one of the shafts is turned while the clutches are in engagement, the belts move as a unit to display ratio data at the various windows in the covers. An optional spring loaded zero set mechanism may be provided to return the belts to a zero time setting representing the start of the flight.

United States Patent Philips Oct. 28, 1975 [75] Inventor: Nicholas A. Philips, Lombard, Ill.

[73] Assignee: Scope Research, Inc., Glen Ellyn, Ill.

[22] Filed: Nov. 28, 1973 [21] Appl. No.: 419,595

[52] US. Cl. 235/61 NV; 235/71 R; 235/125;

[51] Int. Cl G060 1/00 [58] Field of Search 235/71 A, 71 R, 86, 125, 235/133 R, 144 SP, 61 NV [56] References Cited UNITED STATES PATENTS 2,143,892 l/1939 Ludecke et al. 235/71 A 2,176,827 10/1939 Walker 235/125 2,451,784 10/1948 Tellander 235/71 A 2,527,776 10/1950 Taaffe.......... 235/71 A 2,528,010 lO/l950 Lothman.. 235/71 A 2,795,862 6/1957 Poole 235/125 3,353,274 11/1967 Dulhunty 235/71 A 3,392,882 7/1968 Wells 235/144 SP Primary Examiner-Richard B. Wilkinson Assistant Examiner-Vit W. Miska [5 7] ABSTRACT A relatively small, box-like housing contains a pair of spaced parallel shafts journalled in bearings at the opposite ends of the box. A plurality of endless belts are threaded over pulleys or drums mounted on the shafts. Scales of any suitable data or indicia are printed on the belts and displayed through corresponding windows in the cover of the box. Each shaft has one or more clutches interposed between the drums supporting the belts so that, when disengaged, the position of each belt may be changed relative to the positions of the other belts. When any one of the shafts is turned while the clutches are in engagement, the belts move as a unit to display ratio data at the various windows in the covers. An optional spring loaded zero set mechanism may be provided to return the belts to a zero time setting representing the start of the flight.

14 Claims, 14 Drawing Figures U.S. Patant Oct. 28, 1975 Sheet10f3 3,916,155

US. Patent 0m. 28, 1975 Sheet 2 of3 3,916,155

US. Patent Oct. 28, 1975 Sheet 3 Of3 3,916,155

FIG.9

MECHANICAL AIRCRAFT NAVIGATION COMPUTER This invention relates to mechanical computers and more particularly to navigational aid computers for making and executing flight plans.

When preparing or executing a flight plan, a pilot must consider many independently variable factors and calculate how they interact with each other. More particularly, these variables include the amount of fuel on board, the flight speed, the distance flown, weather, el evation, air density and the like. These and other variables limit alternative routing and introduce error factors which often require many successive calculations for each flight. As a result, a pilot is required to devote a substantial amount of time to many interrelated calculations, with a plurality of optional parameters.

Usually, small circular slide rule types of devices are often used by the pilots to interrelate the various parameters. However, these devices are awkward to use, and they present many problems. First, they are very complicated to learn and often require eight to twelve classroom hours of instruction before a pilot dares to rely upon his work. Second, they require two hands to operate, which is sometimes dangerous, as during a flight. Third, the scales are usually small print, on a ruler-like background of vertical dashes. They are difficult to read at a glance so that a pilot must fasten his full attention on them and neglect the aircraft while doing so. Fourth, the penalty for making mistakes may be fatal; therefore, there should be as little room for human error as possible.

As a result of these and other problems, there is a need for a simple, easy to use and read device which may be set before a flight and then operated with one hand and at a glance during the flight. Heretofore, the efforts to provide such a device have not been very successful. For example, some devices are able to display only a limited number of interrelated data elements, carried out to one decimal place, for example, when accuracy requires an interrelation of many alternative data elements in a more precise form.

Some prior art devices involve elastic belts which are stretched or contracted to provide multiplication factors. The stretch increment changes in an analog manner and also varies with time. It must be recalibrated for every use and sometimes cannot be used at all with certain kinds of flight data. For example, an over stretched belt would indicate a greater range than the available fuel permits so that an out of fuel landing would be required at an unanticipated location. Some devices are extremely limited in the number of data scales and tables which can be incorporated therein so that each flight computer device inherently becomes dedicated to the problems of a single airplane type.

Accordingly, an object of this invention is to provide a new and improved mechanical computer. Here, an

object is to provide an aircraft flight planning device using the disclosed type of mechanical computer. In particular, an object is to provide such a device ofa design which may handle a minimum of three independently settable scales and which may in principle be expanded to include any suitable number of independently settable scales.

Another object is to provide a flight planning aid which may be preset to separately store any selected data and may thereafter be operated with one hand and be completely understandable at a glance. Here an ob- 2 ject is to provide a device adaptable to color coded identification of pertinent bits of the data stored therein. In this connection, an object is to continuously provide digital readout of information. In particular, an object is to provide a device for simultaneously solving three or more problems involving ratio calculations.

Still another object is to provide a low cost device which may be operated with a minimum of special training.

Another object is to provide a device which may be zero set at a touch.

In keeping with an aspect of the invention, these and other objects are accomplished by a relatively small, lightweight mechanical computer which may be held in the hand or hung from a dashboard or the like. In greater detail, the computer comprises a small boxlike housing having spaced parallel shafts mounted at opposite ends thereof and rotated by knobs affixed to the ends of the shafts. A plurality of endless belts are threaded over rotatable pulleys or drums mounted on the shaft. One or more clutches are provided between the belts so that the instantaneous position of each belt may be changed relative to the position of each of the other belts. When the clutches are thereafter engaged, the belts move as a unit so that the readout shows the ratios set into the computer which the belt positions have selected. Scales of numbers or other suitable indicia are printed on the belts and displayed through corresponding windows in the cover of the box so that each belt displays information according to the ratios selected when the belts were set. An optional spring zero set mechanism returns the belts to a zero setting when operated.

The nature of a preferred embodiment of the invention may become more apparent from a study of the attached drawings wherein:

FIG. 1 is a perspective view of a small mechanical computer incorporating the principles of the invention;

FIG. 2 is a perspective view of the computer with the top cover opened to disclose the endless belts and the structure for mounting and guiding them for rotating motion;

FIG. 3 is a plan view showing an exemplary shaft assembly at one end of FIG. 2;

FIGS. 4-8 are end views of pulley rollers or drums, clutch, and bearing taken at the lines 4-4 to 8-8 respectively, in FIG. 3;

FIGS. 9-12 are several views showing three different embodiments of zero set mechanisms; and

FIGS. 13 and 14 are perspective views of the back of the computer housing showing suction cup and clip devices, respectively, an exemplary means for attaching the computer to the dash board or another part of an airplane.

In FIG. 1, a relatively small box-like housing 20 has a plurality of color coded control knobs 21, 22, 23 positioned near the corners thereof for controlling the position of movable endless belts inside the housing. Purely by way of example, knob 21 is colored red, knob 22 yellow, and knob 23 green.

A plurality of windows 24-28 are formed in the top cover 29 of the housing and positioned over the belts inside the housing. Therefore, the scale or indicia printed on each belt is exposed to view through the associated window. Each window also has a suitable color code to indicate the relationship between the data displayed therein and the knob for controlling. Again by way of example, windows 24, 27 and 28 are red, win- 3 dovv 25 is yellow. and .window 26 is green. This coating may be accomplished by using colored belts or by colored frames or marks at. the windows, or by any other suitable means.

A cursor 30 may be movably positioned over any one ormore windows to move up or down in directions A or B. Responsive thereto, a hair line 31 on the cursor window may be moved or positioned over any suitable compensating index printed on the cover. For example,

as here shown the hair line 31 is positioned over the outside temperature to compensate the reading in window 28 for an outside temperature of zero;

Any suitable data may be displayed in any of the windows. However, in one specific embodiment window 24 displays the elapsed time into the flight (e.g., 2:l0 for 2 hours, minutes after take off.) Window 25 displays distance flown during the elapsed time, or any one or more suitable scales, such as miles, knots, or kilometers. Window 26 displays fuel, again in one or more scales such as gallons and pounds. Window 27 displays the air density/altitude relationship. Window 28 displays the air pressure/altitude relationship.

The cover 29 of housing may be mounted for removal in any suitable manner. For example, it might be a snap on or hinged cover. When this cover is opened or removed (FIG. 2), a plurality of endless belts 35-37 are exposed to view. Obviously, any suitable number of belts may be provided according to a users needs. For example, to illustrate this flexibility, FIG. 1 shows windows 24-28 arranged in a manner which suggests that four belts might also be used. Two independent scales on one or more belts may be viewed through the windows 27, 28. FIG. 2 has been drawn to illustrate the use of three belts. Thus, it should be apparent that any suitable number of belts may be used. Furthermore, the belts may be replaced quickly and easily so that the computer is not dedicated to any particular data or airplane type. I v 4 To support the endless belts, a pair of spaced parallel shafts 40, 41 are rotatably mounted in opposite ends of a box-like housing. Each shaft carries a plurality of sprocket pulleys, drums, or rollers 42-47 over which the endless belts may be trained. Preferably, these shafts snap into bearings (FIG. 8) of a type which is integrally molded into housing 20. Thus, the shaft may be snapped out to change or replace belts.

Interposed between the rollers or drums 42-47 are one or more clutches 48, 49 for enabling the mechanical position of each of the belts 35-37 to be set independently, to display any selected reading at the associated window. Thus, when clutch 48 is disengaged, belt 35 may be independently set by rotating knob 21 and the left half of shaft belt 40a of shaft 40 controlled thereby. Likewise, the belts 36, 37 may be set independently by rotating knob 22 or 23, respectively assuming that rollers or drums 44 and 46 are merely idlers. Each clutch is an extremely low cost device which has an infinite number of engagement positions.

FIGS. 4-6 are cross sectional plan views of the drums or rollers 42-47. In greater detail, one of the pulleys, drums, or rollers 42 (FIG. 4) has an internal cup-like cavity 50 lined with spaced parallel splines 51 extending in longitudinal alignment with the axis of the drum 42. This particular drum 42 is rigidly attached to and turns with shaft 40a, and, therefore, with knob 21. The mating end of a shaft 40b has a soft rubber collar 52 (FIG. 7) with an outside diameter 53 corresponding to 4 the inside splined diameter 54 of the drum of FIG. 4. Shaft 40b, collar 52, and knob 22 turn as a unit.

Therefore, when knob 22 is pulled out in direction C and away from the housing 20 (as shown in FIG. 3), the rubber collar 52 is pulled out of the cup 50. Then, either of the shaft sections 40a or 40b may be turned independently of the other. When knob 22 is pushed into the housing 20 (direction D), the soft collar 52 is pushed into the splined cup 50. The rubber deforms around the splines 51 to grip the interior cup 50. Thereafter, shafts 40a and 40b turn together as a unit when either of the knobs 21, 22 is turned. After the clutches 48, 49 are re-engaged, all belts rotate together as a unit when any knob is turned.

When any drum (FIG. 5), has a spline 55 therein and the shaft has a mating detent 57 (FIG. 3) thereon, the drum is captured by and must turn with the shaft. On the other hand, when thereis no spline (FIG. 6) the idler drum rotates freely on the shaft. Therefore, in FIG. 3 it is apparent that when knob 22 is turned, drum 43 and the belt trained thereover turn with it. However, drum idler 44 and the belt trained over it does not so turn; they are controlled by knob 23.

Thus, it should now be apparent that with three knobs, the instantaneous positions of any one of the three belts may be set independently of the positions of all other belts. If certain of the belts have interrelated information, they may, of course, also be set simultaneously, as by merely threading them over the same drum or by providing splines 55 and detents 57 on adjacent drums. For example, there may be variables which are related to the airplane type and which vary with air temperature. Therefore, when several belts carrying data relating to the same variable are inserted into the computer, they may be offset from each other in a manner whereby they maybe controlled from the same knob.

For example, assume that there are two scales having a ratio of 1:5 for a first type aircraft and a ratio of 1:6 for a second type aircraft, and further that the setting for both. scales is adjusted for outside air temperature. When the belts are installed in .the computer for use with the first type of aircraft, the 1 on one tape is placed next to 5 on the other tape. When the same two belts are installed in the same computer for the second type aircraft, the 1 is placed next to 6. Thereafter, both tapes are set by the same knob.

The belts 35-37 themselves may be made of any suitable non-elastic material, such as Mylar having suitable indicia or scales 60-64 printed or otherwise formed thereon. There is a row of sprocket holes on each of the belts 35-37 so that no slippage is possible after the belts have been inserted over the sprockets on the pulleys, drums, or rollers 42-47. Since the drum sprockets and belt sprocket holes firmly and mechanically interconnect all of the bands and drums, movement of any belt or drum moves them all if the clutches 48, 49 are engaged. Once the belts are installed, they must pass under the windows in the cover, displaying selected information adjacent a hair line thereon. To further guide and direct the belts, any suitable number of upstanding stationary members 66 may be'formed on the inside cover 29 of the computer. In a preferred embodiment, the guides 66 are integrally molded into the underside of the cover.

To provide for an automatic zero set to drive the- 'belts to theflight time 0:00 (i.e., the parameters at the instant of take off), any of the mechanisms of FIGS.

9--l2 may be provided. Basically, the concept shown in FIG. 9 includes a clock spring 70 which is wound up around shaft 41, as the belts are moved off-normal under the urging of a knob turning shaft 41. A ratchet 71 and latch '72 hold the shaft 41 in any off-normal displaced position, against the urging of the spring 70. As the flight proceeds, the belt having the hour notation is manually advanced to correspond to the elapsed time into the flight. Of course, an optional clock 73 may also be provided to turn shaft 41 and drive the belts in synchronism with real time so that updated parameters are always displayed. When it is desirable to return the readings to a zero position, ratchet 72 is pushed in direction E to pivot around pivot 73 against the urging of a spring 74. Then, the belts are driven back to zero by the energystored in the wound spring 70, until any mechanical catch stops the belts at a suitable zero position. Preferably, the zero readings are those of the time 0:00 at take off; however, this is not necessary.

FIGS. -12 show an alternative zero set mechanism. Here, the shaft 41 terminates in a gear 79 integrally mounted on or turning with the shaft. Pivotally mounted at 80 is a lever arm 81 which is pulled in direction F, by a relatively weak spring 82.

A gear 83 is rotatably mounted on a shaft 84 carried by the lever arm 81. The gear 83 engages gear 79 when lever arm 81 swings in direction G toward shaft 41. Normally, spring 82 pulls lever arm 81 and therefore gear 83 is normally out of engagement with gear 79. Thus, the belts in the mechanical computer may be moved to any position completely independent and free of the mechanism 80-84.

Also mounted on the shaft 84 and turning with gear 83 is a reel 85 for winding or paying out a string or monofilament 86. A relatively strong recoil clock spring 87 winds around shaft 84 as the reel 85 is unwound responsive to a pulling of the string 86. When the string 86 is released, the recoil clock spring 87 unwinds to cause the string 86 to be wound on the reel 85.

A button or knob 89 is attached to the end of string 86, after it is passed through a hole 90 in the cover 29 of the computer. Normally, spring 82 retracts the lever arm 81 and the spring 87 recoils and rewinds the string. Then, the mechanism of FIGS. 10 and 11 merely sits there and does nothing. At this time, the button 89 is pulled in tightly against the outside surface of the cover 29.

To reset the belts to a zero position, the knob 89 is pulled. Since the spring 82 is weaker than the spring 87, the arm 81 responds to the pull and moves gear 83 into contact with gear 79. The reel 85 cannot rotate significantly at this time because of the urging of the stronger recoil clock spring 87.

Once lever arm 81 motion in direction G stops responsive to an engagement between gears 79, 83, reel 85 begins to rotate against the urging of spring 87, as string 86 is pulled therefrom. The rotation of the reel turns gears 83 and 79. Shaft 41 rotates responsive thereto in order to turn the drum 42 and the belt trained thereover. All other belts also move as a unit because they are interlocked by the sprocket and sprocket holes.

As the spring 86 continues to unwind from reel 85, there comes a time when a tab, notch, or stop 92 on one of the belts (such as 35) engages a mechanical stop 93. The person pulling the string feels the stop and releases the button 89. Clock spring 87 then recoils to rewind the string 86 on the reel 85.

Alternatively, any suitable mechanism may be con trolled by stop 93 in order to declutch the belts from the rewind mechanism so that no damage will be caused if the person pulling the string 86 does not respond quickly enough to engagement between notch 92 and stop 93.

Any suitable lighting is provided to enable a display pf the information printed on the belts. Preferably, a battery 95 is connected through a switch 96 to a light bulb 97. The bulb is positioned to illuminate the interior of the housing so that the light glows through the belt material and softly backlights the scale printed on the belts. The interior of the housing may be made of dispersive reflective material to help distribute the light more uniformly.

As shown in FIGS. 13, 14, either suction cups 98, spring clip 99, or another suitable mechanism may be provided to hold and support the computer. For example, it may be mounted on or hung from a dash board or sun shade.

An exemplary operation of the computer will be described next. An assumption is made that a time scale 60 is printed along the left longitudinal half and two altitude scales 61 along the right half of belt 35. Belt 36 has a scale 62 of miles printed along the left longitudinal half, and a scale (not shown) of nautical mile equivalents printed along the right half, either for quick conversion or direct use. Belt 37 has a scale 63 ofgallons" of fuel printed along the left longitudinal half, and a scale 64 of equivalent pounds of fuel printed along the right half, again, either for quick conversion or direct solutions. Belt 37 may be changed to reflect use of gasoline or JP-4 kerosene jet fuels, as required. These scales are arranged as a double slide rule having logarithmic scales printed on the three belts.

These belts enable a solution or ratio problems involving time, distance, and fuel consumption, and they may also be used for in-flight computating density altitude (which is standard sea level altitude, corrected for temperature and pressure), and true airspeed, (which is the airspeed indicated by the airspeed indicator in the aircraft, corrected for temperature and altitude).

To find the ground speed:

a. Pull knob 22 to decouple clutch 48.

b. Set the time (usually zero) in the elapsed flight time window 24.

c. Set an indication of the distance to be flown in window 25.

d. Push knob 22 to couple clutch 48.

e. Set a reading of our hour in window 24, and read the ground speed in window 25.

f. Pull knob 23 to decouple clutch 48.

g. With above described settings of one hour and ground speed, set knob 23 to indicate the number of gallons which the airplane consumes per hour in window 26.

h. Push knob 23 to couple clutch 48. All inputs have now been entered for one flight.

For example, if 7.7 gallons are on board, use any knob to set 7.7 in window 26, and read 46 pounds of fuel which is also displayed in window 26. From window 24 it can be seen that 36% minutes of flight remain. The fact that the airplane will travel 93 miles during this time is seen in window 25.

To plan a flight, a pilot may add the weights of all passengers and baggage. Then, suppose that he finds that he has 54 pounds of carrying capacity left for fuel. If the airplane flies miles per hour and burns 10 7 gallons per hour, he simply sets one hour in the window 24, 110 in the window 25, and 10 in the window 26. The problem is thereafter solved by adjusting to a reading of 54 pounds in the window 26.

Reading across, the pilot observes 38 minutes in the window 24, 105 miles in the window 25, and 54 pounds or the equivalent eight gallons in window 26. Once the scales are set for a particular flight, it is only necessary to insert any one variable, and directly read answers in the remaining windows.

When a pilot operates out of an airport located at a high elevation, be needs to know how much runway his aircraft will use during takeoff, based on temperature and altitude above sea level, or density altitude. Normally, this determination is a rather cumbersome procedure. However, with the inventive computer, the solution is obtained as follows:

1. Set one hour in window 24.

2. Set the indicated airspeed in window 25. Lock clutch 48.

3. Set the outside air temperature on cursor 30.

4. Set pressure altitude in window 27 by turning knob 21.

5. Read density altitude directly in upper window 27. 6. Read the true airspeed of aircraft in window 25. Any other time/distance/fuel/altitude inputs and the solutions of many problems may be obtained in th same manner.

Therefore, this mechanical computer is particularly useful to pilots for preflight planning and for enroute corrections or observations. The pilot may observe how much fuel is on board, and from that determine how much further he may safely fly or, with weather considerations, where he should stop to refuel. He may compute his estimated time of arrival'at a particular destination, or determine the ultimate range of his aircraft. He may also calculate the take-off distance required from airports at higher elevation. Since it is relatively simple to operate, it is easy for students to learn to operate the computer. No retention of the principles involved is required by the student. Instructions printed on the cover explain how to operate the unit even to a novice.

A further feature of the invention is that the zero preset mechanism may be arranged or adjusted to reset the computer to any desired point or reading, and according to any scale. For example, in some cases, the computer may be reset to one hour, which displays the distances, fuel consumption, or the like for a unit of time. Likewise, the arrangement may be to reset to a basic unit of fuel, such as a pound or a gallon. Still further, it is very easy to use a push button for each tape so that the computer will zero" reset to any particular point of any selected tape according to the button pushed. For example, this push button might operate lever 93 on FIG. 12 to catch tab 92 on the tape associated with the push button. Hence, any references to the zero set should be construed broadly enough to cover any pre-set position.

The internal lighting and digital readout eliminate many errors which result from having to interpolate solutions, especially during periods of poor visibility or while preoccupied with flying.

Those skilled in the art will readily perceive how modifications may be made. Therefore, the appended claims should be construed to cover all equivalent structures.

1 claim:

1. A mechanical computer comprising a box-like housing having a cover with a plurality of windows therein, each of the two opposite ends of said housing containing one shaft parallel to that end, the two shafts forming a pair of spaced parallel shafts rotatably journalled and removably supported in bearings affixed to said housing, a plurality of endless non-elastic belts threaded over oppositely disposed pulleys or drums mounted on each of the two shafts, scales of indicia formed on the belts and displayed through corresponding ones of said windows in the cover of the box, clutch means interposed in at least one of said shafts and between the pulleys or drums supporting the belts for selectively interconnecting sections of each shaft so that when the clutch is disengaged the position of each individual belt may be changed relative to the positions of the other belts, and means responsive to engagement of said clutch for moving all of the belts as a unit to display data at the various windows when any one of the shafts is rotated while the clutches are in engagement.

2. The computer of claim 1 and normally disengaged spring loaded zero set means for automatically returning the belts to a zero time setting, and meansfor manually engaging said zero set means and said belts to drive said belts to said zero time setting.

3. The computer of claim 1 wherein at least one of said belts includes at least a row of sprocket holes longitudinally distributed along the length thereof and at least one of said pulleys or drums for supporting said one belt, said one pulley or drum including mating sprockets whereby said one belt and said one sprocket cannot slip relative to each other.

4. The computer of claim 1 wherein the rotational movement of each of said shaft sections is controlled by an individually associated color coded knob, and color coding means for identifying the window displaying the data on the belt set by a correspondingly color coded knob.

5. The mechanical computer of claim 1 wherein one of said belts carries indicia of time in terms of elapsed hours, and clock means for driving said belts in synchronism with real time as said time is indicated by the indicia on said one belt.

6. The mechanical computer of claim 1 and movable cursor means associated with at least one of the windows and indexed for compensating the'reading at said one window for an additional variable.

7. The mechanical computer of claim 1 wherein said clutch means comprises an internal cup-like cavity formed in at least one of the pulleys or drums, said cavity having at least one spline extending in substantially longitudinal alignment with the axis of the pulley or drum, said one pulley or drum being rigidly attached to and turning with one of said sections of one of the shafts, the mating end of another section of said one shaft having a soft rubber collar with an outside diameter corresponding to the inside splined diameter of the drum, whereby said two sections may be interconnected or disconnected by pulling or pushing said knob.

8. The mechanical computer of claim 1 wherein said indicia comprises flight planning aid means which may be preset to separately store any selected data.

9. The mechanical computer of claim 1 and key means for interconnecting said shafts with one of said pulleys or drums to cause them to rotate as a unit with the associated shaft, the pulleys or drums of the shaft opposite said interconnected pulleys or drums being 9 free to rotate on one of said shafts, as an idler.

10. The mechanical computer of claim 1 and means for internally lighting said box to display the scales of said indicia on said belts.

11. The mechanical computer of claim 1 and attach ing means forming on said housing for mounting said housing on a larger structure.

12. The mechanical computer of claim 1 wherein the removably supported shafts provide means for changing said belts to substitute new scales of indicia.

13. The mechanical computer of claim 1 and zero set means for automatically setting said belts to a predetermined position, said zero set means comprising a pair of springs having different strengths relative to each other, and means whereby a single reset operation first engages said reset means with one of said shafts by pulling against the force of the weaker one of said pair of springs to store energy therein said continued single reset operation driving said belts against the force of the stronger one of said pair of springs to store energy therein, and termination of said single reset operation enables said zero set means to disengage and return to normal under the force of the energy stored in said pair of springs.

14. The mechanical computer of claim 1 wherein each of said shafts include a clutch means, each clutch comprising an internal cup-like cavity in a pulley or drum attached to the end of one shaft section, said cavity being lined with a plurality of spaced parallel splines extending in substantial'longitudinal alignment with the axis of the pulley or drum, the mating end of another section of the shaft having a soft rubber collar attached thereto, the outside diameter of said rubber collar corresponding to the inside splined diameter of the drum cavity, key means for interconnecting some of said pul leys or drums to rotate as a unit with the associated shaft, the pulleys or drums on the shaft opposite said interconnected pulleys or drums being free to rotate on their shafts, each of said belts including a row of sprocket holes longitudinally distributed along the length thereof, each of said pulleys or drums including mating sprockets whereby all of said belts and sprockets are interlocked so that they cannot slip relative to each other, and cursor means associated with at least one of the windows for compensating the reading at said one window for the ambient changes in a variable. l 

1. A mechanical computer comprising a box-like housing having a cover with a plurality of windows therein, each of the two opposite ends of said housing containing one shaft parallel to that end, the two shafts forming a pair of spaced parallel shafts rotatably journalled and removably supported in bearings affixed to said housing, a plurality of endless non-elastic belts threaded over oppositely disposed pulleys or drums mounted on each of the two shafts, scales of indicia formed on the belts and displayed through corresponding ones of said windows in the cover of the box, clutch means interposed in at least one of said shafts and between the pulleys or drums supporting the belts for selectively interconnecting sections of each shaft so that when the clutch is disengaged the position of each individual belt may be changed relative to the positions of the other belts, and means responsive to engagement of said clutch for moving all of the belts as a unit to display data at the various windows when any one of the shafts is rotated while the clutches are in engagement.
 2. The computer of claim 1 and normally disengaged spring loaded zero set means for automatically returning the belts to a zero time setting, and means for manually engaging said zero set means and said belts to drive said belts to said zero time setting.
 3. The computer of claim 1 wherein at least one of said belts includes at least a row of sprocket holes longitudinally distributed along the length thereof and at least one of said pulleys or drums for supporting said one belt, said one pulley or drum including mating sprockets whereby said one belt and said one sprocket cannot slip relative to each other.
 4. The computer of claim 1 wherein the rotational movement of each of said shaft sections is controlled by an individually associated color coded knob, and color coding means for identifying the window displaying the data on the belt set by a correspondingly color coded knob. Pg,20
 5. The mechanical computer of claim 1 wherein one of said belts carries indicia of time in terms of elapsed hours, and clock means for driving said belts in synchronism with real time as said time is indicated by the indicia on said one belt.
 6. The mechanical computer of claim 1 and movable cursor means associated with at least one of the windows and indexed for compensating the reading at said one window for an additional variable.
 7. The mechanical computer of claim 1 wherein said clutch means comprises an internal cup-like cavity formed in at least one of the pulleys or drums, said cavity having at least one spline extending in substantially longitudinal alignment with the axis of the pulley or drum, said one pulley or drum being rigidly attached to and turning with one of said sections of one of the shafts, the mating end of another section of said one shaft having a soft rubber collar with an outside diameter corresponding to the inside splined diameter of the drum, whereby said two sections may be interconnected or disconnected by pulling or pushing said knob.
 8. The mechanical computer of claim 1 wherein said indicia comprises flight planning said means which may be preset to separately store any selected data.
 9. The mechanical computer of claim 1 and key means for interconnecting said shafts with one of said pulleys or drums to cause them to rotate as a unit with the associated shaft, the pulleys or drums on the shaft opposite said interconnected pulleys or drums being free to rotate on one of said shafts, as an idler.
 10. The mechanical computer of claim 1 and means for internally lighting said box to display the scales of said indicia on said belts.
 11. The mechanical computer of claim 1 and attaching means forming on said housing for mounting said housing on a larger structure.
 12. The mechanical computer of claim 1 wherein the removably supported shafts provide means for changing said belts to substitute new scales of indicia.
 13. The mechanical computer of claim 1 and zero set means for automatically setting said belts to a predetermined position, said zero set means comprising a pair of springs having different strengths relative to each other, and means whereby a single reset operation first engages said reset means with one of said shafts by pulling against the force of the weaker one of said pair of springs to store energy therein said continued single reset operation driving said belts against the force of the stronger one of said pair of springs to store energy therein, and termination of said single reset operation enables said zero set means to disengage and return to normal under the force of the energy stored in said pair of springs.
 14. The mechanical computer of claim 1 wherein each of said shafts include a clutch means, each clutch comprising an internal cup-like cavity in a pulley or drum attached to the end of one shaft section, said cavity being lined with a plurality of spaced parallel splines extending in substantial longitudinal alignment with the axis of the pulley or drum, the mating end of another section of the shaft having a soft rubber collar attached thereto, the outside diameter of said rubber collar corresponding to the inside splined diameter of the drum cavity, key means for interconnecting some of said pulleys or drums to rotate as a unit with the associated shaft, the pulleys or drums on the shaft opposite said interconnected pulleys or drums being free to rotate as idlers on their shafts, each of said belts including a row of sprocket holes longitudinally distributed along the length thereof, each of said pulleys or drums including mating sprockets whereby all of said belts and sprockets are interlocked so that they cannot slip relative to each other, and cursor means associated with at least one of the windows for compensating the reading at said one window for the ambient changes in a variable. 